In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields.
Replace the empty __nfct_init_offset member with a struct_group() to mark the region of struct nf_conn that should be initialized to zero, allowing memset() to correctly reason about the size of the write.
Signed-off-by: Kees Cook keescook@chromium.org --- include/net/netfilter/nf_conntrack.h | 20 ++++++++++---------- net/netfilter/nf_conntrack_core.c | 4 +--- 2 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index cc663c68ddc4..51004fce2937 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -101,24 +101,24 @@ struct nf_conn { struct hlist_node nat_bysource; #endif /* all members below initialized via memset */ - struct { } __nfct_init_offset; - - /* If we were expected by an expectation, this will be it */ - struct nf_conn *master; + struct_group(init, + /* If we were expected by an expectation, this will be it */ + struct nf_conn *master;
#if defined(CONFIG_NF_CONNTRACK_MARK) - u_int32_t mark; + u_int32_t mark; #endif
#ifdef CONFIG_NF_CONNTRACK_SECMARK - u_int32_t secmark; + u_int32_t secmark; #endif
- /* Extensions */ - struct nf_ct_ext *ext; + /* Extensions */ + struct nf_ct_ext *ext;
- /* Storage reserved for other modules, must be the last member */ - union nf_conntrack_proto proto; + /* Storage reserved for other modules, must be the last member */ + union nf_conntrack_proto proto; + ); };
static inline struct nf_conn * diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 5c03e5106751..b05eb64ec788 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -1527,9 +1527,7 @@ __nf_conntrack_alloc(struct net *net, ct->status = 0; ct->timeout = 0; write_pnet(&ct->ct_net, net); - memset(&ct->__nfct_init_offset, 0, - offsetof(struct nf_conn, proto) - - offsetof(struct nf_conn, __nfct_init_offset)); + memset(&ct->init, 0, sizeof(ct->init));
nf_ct_zone_add(ct, zone);